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Published byOswin Holmes Modified over 9 years ago
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Kunihito IOKA (Osaka Univ.) 1.Observation 2.Fireball 3.Internal shock 4.Afterglow 5.Jet 6.Central engine 7.Links with other fields 8.Luminosity-lag 9.X-ray flash 10.Summary
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1. Observation Gamma-Ray Burst Brightest object Vela satellites in 1967 Origin has been a puzzle
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~ 1000 events/yr Angular distribution Isotropic
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Spatial distribution Homogeneous in Euclidean Inhomogeneous
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Duration Long-soft Short-hard Long burst Short burst
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Spectrum Band spectrum Non-thermal
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Afterglow Beppo-SAX in 1997 X-ray Radio
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Optical → Redshift Redshift
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Luminosity Time GRB Summary of observation ~ 1000 events/yr Isotropic, Inhomogeneous ~ 200 keV 10 -3 s ~ 10 3 s : short, long Afterglow X-ray Optical Radio Redshift >msec
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2. Fireball Compactness problem Relativistic motion MeV MeV
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Fireball +Baryon Thermal
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Central engine Optically thick region Internal shocks External shocks ? ISM Internal-External shock model time Luminosity
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3. Internal shock Two shell collision Kobayashi,Piran&Sari(97) Many shell
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Time scale Pulse width Pulse interval Nakar&Piran(02)
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4. Afterglow External shock Hydrodynamics
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① Electron Fermi acceleration ② Magnetic field Relativistic shock Jump condition Electron synchrotron emission
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Spectrum
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Collapsar, Hypernova
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reverse shockforward shock Shock emission Optical flash
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5. Jet Jet & Relativistic beaming ・ Relativistic beaming ・ Jet Jet in afterglow :sideways expansion Energy, Event rate, Model
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Total Break in afterglowPolarization A few %
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Total energy
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6. Central engine ① Collapse of massive star ② Mergers of compact objects ・Baryon free ・Location within host galaxies ・GRB - Supernova (e. g. ,SN1998bw) ?High ambient gas density ?? Collapsar, Hypernova
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Host galaxy
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SN1998bw-GRB980425 Lightcurve Fe line
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7. Links with other fields CR, HE, HE Cosmology
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8. Luminosity-lag XX Luminosity Time ・Standard candle ? ・Brighter than SNe Ia ・Less extinction ApJ,554,L163(01)
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Viewing angle of a single jet ? ? ? ⇒Luminosity - lag relation ?
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Thin jet Emissivity ~Band spectrum Spectrum
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Luminosity-Lag Relation Lag:
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Pulse profile Luminosity-width FRED(Fast Rise Exponential Decay)
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Viewing angle ① Peak luminosity - spectral lag relation ② Peak luminosity - variability relation ③ Luminosity - width relation GRB 980425 A typical GRB ⇒Association of GRBs with SNe
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9. X-ray flash
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Off-axis GRB
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Flux/Fluence Ratio ApJ,571,L31(02)
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VolumeViewing angle
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10. Summary GRB : Internal shock Afterglow : External shock Jet Viewing angle Various relations, X-ray flash Central engine ??? Collapsar? Merger? CR, HE, HE , GW, Cosmology
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